When displaying a mark on a part of information provided by the information provider, the following technique is used. The mark issuer issues the mark information beforehand to the information provider. The information provider stores the mark information in an information providing server. According to a providing information display request by a user, the mark information together with providing information are obtained and displayed.
Also, there is a following technique. The mark issuer notifies the information provider of information on the location of the mark beforehand. The information provider embeds location information of the mark information in the providing information, and obtains the providing information and the mark information from the mark location, and displays the providing information and the mark information according to a display request of the user.
However, according to the above-mentioned conventional technologies, when displaying a mark on a part of information provided by the information provider, management of the issued marks depends on the information provider. Accordingly, for example, if the term of validity is set for issuing the mark, there is a problem in that the mark can be used invalidly since the information provider can issue the mark information even after the term of validity is expired.
In addition, since the mark provider notifies the information provider of the information on the location of the mark information beforehand, information for obtaining the mark information is embedded in the information provided by the information provider. Therefore, there is a problem in that an information provider that intends to use the mark information invalidly can produce providing information by using the location information and can provide the providing information from the information providing server as if to provide providing information validly.